Shape Entropy and the Time Scales for Thermodynamics in Biological Systems

Abstract

Mitochondrial inner membranes show coexistence between tubular and lamellar structures. The lipid molecules in these membranes represent a mobile pool whose observed redistribution on the time scale of seconds ensures that the chemical potentials of the lipid in the tubes and in the lamella be equal. This allows for easy inter-conversion of these shapes and makes possible the entropic stabilization of an ensemble of different shapes. Such shape entropy stabilization on a timescale of seconds accounts for observed morphology.